Molding method and resin moldings

ABSTRACT

A molding method which includes charging a resin composition in molten state containing not less than 7 wt % to less than 30 wt % of a fibrous fiber (A) and more than 70 wt % to not exceeding 93 wt % of a resin (B) into a die for shaping purpose when a temperature of the die is in the range of [the Vicat softening point minus 20° C.] of resin (B) to less than a melting point thereof, when resin (B) is crystalline resin, or when a temperature of the die is in the range of [the Vicat softening point minus 20° C.] to [the Vicat softening point plus 20° C.] of the resin (B), when resin (B) is non-crystalline resin, cooling the die after shaping to temperature which allows taking-out of a molded product.

TECHNICAL FIELD

This invention relates to a resin molding to which a fibrous filler isadded and a method of molding thereof. Particularly the resin molding isused frequently in the fields of automobiles and housing facilitieswhere rigidity and appearance are required. For example, in theautomobile industry, the resin molding is used in instrumental panelparts, door parts, body panel, floor lid, side steps and the like. Inthe housing facility industry, the resin molding is used inprefabricated bath parts, assembled furniture, doors, roads, railroadsound-proof walls and the like.

BACKGROUND ART

Fiber reinforced resin molding is used extensively in a variety offields including automobiles, housing facilities, and medical appliancesas well as electric appliances due to its light-weight and high-rigidityfeatures.

As for this fiber-reinforced resin molding, GFRP (Glass Fiber ReinforcedPlastics) produced by molding using glass fiber as the reinforcing fiberand polypropylene, which is a type of thermoplastic resin, as the resin,and the like are well known.

The fiber-reinforced resin molding of this sort is used in the currentautomobile industry for main components of modules such as front-endmodule, door module and the like, torque converter bracket and intakesystem parts.

For example, as a method for manufacturing these fibrous resin moldings,injection molding and hollow molding are known which are used formanufacturing of these moldings by molding propylene homopolymer,low-density polyethylene and polypropylene composition containing glassfiber as the reinforcing fiber and talc (see for example Japanese PatentApplication Laid-open No. Hei 9-328586).

The composition is molded at a die temperature higher than 100° C. toproduce a resin molding with high-rigidity and uniform wall thickness.

However, when a fiber-reinforced resin molding is manufactured by theconventional molding method, lifting of the reinforcing fiber orprotrusion of weld area may easily appear on the molding surface. Thisis not desirable from appearance viewpoints and poses a problem of lackof good design features.

Conventionally a few attempts have been made for solving the problem,such as film pasting on the surface of the resin molding or multiplayercontaining no fibrous layer. However, these methods are not effectivefrom industrial viewpoints. Although an alternative to reduce amount ofthe reinforcing fiber to be added is proposed, with this method,improvement of physical properties of the fiber-reinforced resin moldingis not possible.

Due to the reasons as described above, conventional fiber-reinforcedresin moldings were used mostly at such portion where appearance qualitywas not considered to raise a significant problem.

DISCLOSURE OF THE INVENTION

One object of the present invention in these problem areas is to providea resin molding with favorable appearance without exposure of fibrousfiller, and a molding method thereof.

The applicant investigated substantially methods for molding resincomposition to which fibrous filler is added and found that overallappearance was improved by controlling molding conditions as well asexposure of the fibrous filler and warpage deformation were eliminated.This invention has been completed based of these findings.

The method for molding a resin molding according to this inventionrelates to injection molding method for manufacturing a resin molding bycharging a resin composition including fibrous filler (A) and resin (B)into a die by injection, wherein the resin composition contains not lessthan 7 wt % to less than 30 wt % of the fibrous filler (A) and more than70 wt % to not exceeding 93 wt % of the resin (B), and that comprisesthe steps of;

(a) charging the resin composition in molten state into the die forshaping purpose when a temperature of the die is in the range of [theVicat softening point minus 20° C.] of the resin (B) to lower than amelting point thereof, when the resin (B) is crystalline resin, orcharging the resin composition in molten state into the die for shapingpurpose when a temperature of the die is in the range of [the Vicatsoftening point minus 20° C.] to [the Vicat softening point plus 20° C.]of the resin (B), when the resin (B) is non-crystalline resin; and

(b) cooling down the die to a temperature which allows taking-out of amolded product, after shaping is performed (injection molding).

As for the fibrous filler (A), such as glass fiber, carbon fiber,magnesium sulfate fiber, potassium titanate fiber, titanium oxide fiber,magnesium oxy-sulfate fiber or organic filler, organic synthesis ornatural fibers and the like can be used. Fiber diameter of the fibrousfiller (A) should preferably be less than 25 μm.

As for the resin (B), it is preferable to use thermoplastic resin, andeither crystalline resin or non-crystalline resin may be used. Forexample, as for the crystalline resin, polyolefin resin, polyester resinsyndiotactic polystyrene and the like can be used. As fornon-crystalline resin, there is no limitations and for example,polyvinylchloride, polycarbonate, acrylic resin, polystyrene and thelike can be used.

According to the present invention, when the resin (B) is crystallineresin, the resin composition in molten state is charged into the die byinjection for shaping purpose when the temperature of the die is in therange of [the Vicat softening point minus 20° C.] of the resin B to lessthan the melting point thereof, when the resin (B) is crystalline resin.When the resin (B) is non-crystalline resin, the resin composition inmolten state is charged into the die by injection for shaping purposewhen the temperature of the die is in the range of [the Vicat softeningpoint minus 20° C.] to [the Vicat softening point plus 20° C.] of theresin B. This operation allows improved fluidity of the resincomposition at a contact of the die and the resin composition,suppresses lifting of the fibrous filler and at the same time, a moldsurface of the die is well transcribed onto the resin composition.

If shaping is attempted by charging the resin composition in moltenstate into the die for shaping purpose when temperature of the die isless than [the Vicat softening point minus 20° C.] of the resin (B),suppression of lifting of the fibrous filler is not possible due toreduction in fluidity of the resin composition. In other words, forobtaining a resin molding having an emboss, accurate transcription of amolded surface of the die on the resin composition is not possible andan emboss is not formed as designed. In addition, for obtaining a resinmolding having mirror surface, high-gloss feature and anti-scratchingfeature are deteriorated and surface roughness is worsened resulting inan undesirable appearance. While if the die temperature is set to higherthan melting point of the resin (B) or [the Vicat softening point plus20° C.], molding cycle becomes longer and this is not advantageous fromindustrial viewpoints if production efficiency and energy efficiency aretaken into considerations.

Further, by keeping the resin composition in the range of not less than7 wt % to less than 30 wt % of the fibrous filler (A) and more than 70wt % to not exceeding 93 wt % of the resin (B), whole appearance of theresin molding can be improved while prescribed strength is maintained.

When the fibrous filler (A) is less than 7 wt %, improvements ofphysical properties of the resin molding are not possible. When thefibrous filler (A) is not less than 30 wt %, it is difficult to preventlifting of the fibrous filler (A).

According to the present invention, it is possible to manufacture aresin molding while suppressing lifting of the fibrous filler (A) andmaintaining the desired strength. When embossing is provided to moldedsurface of the die, by suppressing lifting of the fibrous filler (A), itis possible to obtain a resin molding to which an emboss with nearlysame emboss depth provided on the mold surface is formed. When moldsurface of the die is mirror processed, it is possible to obtain a resinmolding with fine surface roughness and good surface gloss.

Alternatively, the method for molding a resin molding according to thepresent invention may be such that a resin composition containingfibrous filler (A) and resin (B) is extruded to be converted into amolten parison, the parison is held in a die and, gas is blown into theparison inside, wherein the resin composition contains not less than 7wt % to less than 30 wt % of the fibrous filler (A) and more than 70 wt% to not exceeding 93 wt % of the resin (B), gas is blown into theparison inside when temperature of the die is in the range of [the Vicatsoftening point minus 20° C.] of the resin B to less than the meltingpoint thereof and shaping is performed when the resin (B) is crystallineresin, or gas is blown into the parison inside when temperature of thedie is in the range of [the Vicat softening point minus 20° C.] to [theVicat softening point plus 20° C.] and shaping is performed when theresin (B) is non-crystalline resin, and after the shaping is performed,the die is cooled down to a temperature which allows taking-out of amolded product (hollow molding method).

The fibrous filler (A) and the resin (B) used here are those mentionedpreviously.

According to the present invention, even with the hollow molding methodhaving lower pressing pressure to the mold surface of the die comparedto the molding method (injection molding) of the present inventionmentioned previously, it is possible, by controlling the dietemperature, to improve die transcription rate through improvement offluidity of the resin composition, to suppress lifting of the fibrousfiller and to improve appearance of the whole resin molding.

In the molding method of the present invention, when the resin (B) iscrystalline resin, it is preferable that after shaping of the resincomposition is performed, temperature of the die is held for the presetperiod in the range of [crystallization temperature minus 15° C.] to[crystallization temperature plus 10° C.] of the mold (B).

When a crystalline resin is used as the resin (B), warpage may be causedeasily to the molded product depending on array direction of reinforcingfibers. For this reason, careful attention is required for productdesign, die design and molding processing conditions in manufacturing aresin molding.

According to the condition, when the resin (B) is crystalline resin,after temperature for the die is held for the preset period in the rangeof [crystallization temperature minus 15° C.] to [crystallizationtemperature plus 10° C.], and the die is cooled down to a temperaturewhich allows taking-out of a molded product. This operation allowsoverall control of crystallization of the whole resin molding,suppressing lifting of fibrous filler, eliminating warpage deformationthereby, and improving appearance of the whole resin molding anddimensional accuracy.

When temperature of the die is held at lower than [crystallizationtemperature minus 15° C.] of the resin (B) for the preset time,crystallization rate of the resin becomes faster, and suppression ofshrinkage and of warpage deformation is difficult. When temperature ofthe die is held at higher than [crystallization temperature plus 10° C.]of the resin (B) for the preset time, molding cycle becomes longer sothat crystallization rate may be slowed, and this is not advantageousfrom industrial viewpoints in production efficiency and energyefficiency.

Further, by controlling cooling process of crystalline resin and othernon-crystalline resin under different conditions, it is possible toselect an appropriate molding cycle depending on the types of the resinand to improve the productivity.

In the molding method of the present invention, it is preferable thatshaping of the resin composition is performed when temperature of thedie is in the range of [the Vicat softening temperature minus 10° C.] to[melting point minus 10° C.] of the resin (B), if resin (B) iscrystalline resin, and when temperature of the die is in the range of[the Vicat softening temperature minus 10° C.] to [the Vicat softeningtemperature plus 10° C.] of the resin (B), if the resin (B) isnon-crystalline resin.

When the resin (B) is crystalline resin, if temperature of the die ishigher than the melting point of the resin (B), molding cycle becomeslonger and the productivity is deteriorated.

According to this condition, when the resin (B) is crystalline resin, byperforming shaping of the resin composition when temperature of the dieis in the range of [the Vicat softening temperature minus 10° C.] to[melting point minus 10° C.] of the resin (B), it is possible totranscribe a mold surface of the die well onto the resin compositionwithout deteriorating the productivity. When the resin (B) isnon-crystalline resin, by performing shaping of the resin compositionwhen temperature of the die is in the range of [the Vicat softeningtemperature minus 10° C.] to [the Vicat softening temperature plus 10°C.] of the resin (B), it is possible to transcribe a mold surface of thedie well onto the resin molding similarly without deteriorating theproductivity.

In the molding method of the present invention, it is preferable thatafter shaping of the resin composition is performed, temperature of thedie is held for the preset time in the range of [crystallizationtemperature minus 10° C.] to [crystallization temperature] of the resin(B), for such a case where the resin (B) is crystalline resin.

According to this condition, when the resin (B) is crystalline resin, byholding temperature of the die in the range of [crystallizationtemperature minus 10° C.] to [crystallization temperature] of the resin(B), it is possible to improve the productivity with an appropriatemolding cycle and to suppress lifting of the fibrous filler (A) and atthe same time, warpage deformation of the resin is eliminated therebyimproving appearance of the whole resin molding and dimensionalaccuracy.

In the molding method of the present invention, it is preferable thatthe resin composition contains not less than 10 wt % to not exceeding to25 wt % of the fibrous filler (A).

According to this condition, by keeping the fibrous filler (A) contentin the resin composition in the range of not less than 10 wt % to notexceeding to 25 wt %, physical properties of the resin molding can beimproved appropriately and lifting of the fibrous filler (A) can besuppressed.

A resin molding according to the present invention is manufactured bythe molding method of the present invention as mentioned previously.

According to the present invention, similar operational effects asattained by the molding method mentioned previously can be obtained, andit is possible to suppress lifting of the fibrous filler (A) whilemaintaining the desired strength. A resin molding thus obtained can beused in automobile and housing facility industries and the like whererigidity and appearance are required.

Alternatively, a resin molding according to the present invention mayinclude a resin composition containing not less than 7 wt % to less than30 wt % of the fibrous filler (A) and more than 70 wt % to not exceeding93 wt % of the resin (B), wherein surface roughness is less than 5 μm,and an image representation of 1 mm square rectangular frame beingreflected-on the surface can be discriminated.

When surface roughness of a resin molding to which the fibrous filler(A) is added is more than 5 μm, the fibrous filler (A) may appear easilyon the surface of the resin molding. Besides, even if the fibrous filler(A) is not exposed to the surface of the resin molding, unevenness maybe easily formed on the surface by the fibrous filler (A).

When an image representation of 1 mm square rectangular frame beingreflected on the surface can not be discriminated (image clarity is notsatisfactory), it indicates in many cases that either surface of theresin molding is rough or anti-scratching feature and high-gloss featureof the resin molding are not satisfactory.

According to the present invention, surface roughness is less than 5 μmand an image representation of 1 mm square rectangular frame beingreflected on the surface is formed so as to be discriminated, it ispossible to present a resin molding with good appearance by suppressinglifting of the resin filler (A).

Alternatively, a resin molding according to the present invention maycontain a resin composition containing not less than 7 wt % to less than30 wt % of the fibrous filler (A) and more than 70 wt % to not exceeding93 wt % of the resin (B), and if it has an emboss on the surface, and itsatisfies either of the following two cases: (1) In the case of embossbeing provided on the whole surface of the molding, rate of dietranscription is more than 90%, (2) In the case of emboss being providedin part on the molding, rate of die transcription is more than 90% andsurface roughness of such an area where there is no emboss is less than5 μm.

The rate of die transcription can be expressed by a ratio (h/H) where Hmeans depth of emboss of the die and h means depth of emboss of theresin molding formed by this die. When this rate of die transcription isless than 90%, lifting of the fibrous filler (A) is caused andtranscription of the emboss is not made satisfactorily resulting in poorappearance.

For resin molding having emboss in part on the resin molding, whensurface roughness at a non-emboss area where there is more than 5 μm,lifting of the fibrous filler (A) becomes easily remarkable resulting inpoor appearance and lack of image clarity.

According to the present invention, the resin molding satisfying either(1) or (2) mentioned above, may suppress lifting of the fibrous filler(A) and present good appearance.

As for the resin molding according to the present invention, it ispreferable that the resin composition contains not less than 10 wt % tonot exceeding to 25 wt % of the fibrous filler (A).

According to this composition, by the fact that a resin compositioncontains not less than 10 wt % to not exceeding to 25 wt % of thefibrous filler (A), a resin composition is able to suppress lifting ofthe fibrous filler (A) and to present a resin molding with goodappearance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view showing an injection molding machine used inthe molding method relating to the first embodiment of the presentinvention.

FIG. 2 is a sectional view showing a hollow molding machine used in themolding method relating to the second embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention are described hereafterreferring to the drawings.

FIRST EMBODIMENT

FIG. 1 is a sectional view of injection molding machine 1 used in themolding method relating to the first embodiment of the presentinvention.

Injection molding machine 1 produces resin molding having the prescribedshape from resin compositions in which fibrous filler (A) andthermoplastic resin (B) are mixed, and has injection device 11, die 12,and clamping device 13.

The injection device 11 plasticizes resin composition being charged andinjects it to the die 12, has cylinder 111 equipped with heater 111A,screw 112 which is arranged in the cylinder 111, hopper 113 throughwhich raw materials are charged in the cylinder 111, hydraulic device114 used for turning of the screw 112, and nozzle 115 connecting thecylinder 111 and die 12.

The resin composition being charged from the hopper 113 and heated bythe heater 111A of the cylinder 111 is kneaded by the screw 112 to beplasticized, moved to the nozzle 115 and is injected into the diethrough nozzle 115 by high-pressure.

The die 12 has the fixed die 12A mounted to the nozzle 115 and a movabledie 12B being retractable with this fixed die 12A, and the movable die12B moves forward and backward by operation of the clamping device 13,thus the die 12 performs opening and closing operations. While the fixeddie 12A and movable die 12B are being engaged, a cavity is formed insidethis engagement. A temperature control function (not illustrated) forcontrolling temperature of the die 12 is equipped in the die 12.

There are various surface conditions of die 12 which is surface treateddepending on applications of the resin molding, for example, mirrorfinish less than 0.5 S, embossing, pattern printing, character andgraphical printing, or any combination thereof.

The clamping device 13 holds a closed state of the die 12 by a clampingforce sufficiently large to resist against opening/closing operations ofthe die 12 and injection pressure of the injection device 11. Forexample, this clamping device 13 may be a direct pressure type clampingdevice which transmits a force directly to a molding die withoutchanging a driving power generated by the driving device such ashydraulic cylinder and the like, or a toggle type clamping device whichamplifies a force generated by the driving device such as hydrauliccylinder and the like by means of combinations of links to generate alarge clamping force to the molding die.

Hereafter a method of molding of a resin composition using injectionmolding machine 1 shown above will be described.

First, the clamping device 13 is operated, so that the movable die 12Bis then moved and clamping of the die 12 is performed

Second, after clamping of the die 12 is completed, the injection device11 is operated, and the hydraulic device 114 starts turning of the screw112. Resin composition being charged from the hopper 113 is fed fromrear end to front end of the screw due to turning of the screw 112, andkneaded and melted while being heated by the heater 111A of cylinder111.

The resin composition thus melted moves to nozzle 115, is pressurized bythe prescribed pressure at front end of the screw 112, and is injectedinside the die 12 under he pressure. It is then filled into the die 12to be shaped, and the hydraulic device 114 stops turning of the screw112 by detecting a pressure of the molten resin composition.

It is preferable that when the thermoplastic resin (B) is crystallineresin, a temperature of the die 12 (temperature at shaping) iscontrolled by the temperature control mechanism and is set in the rangeof [the Vicat softening point Tb minus 20° C.] of the thermoplasticresin (B) to the melting point thereof. For such a case where thethermoplastic resin (B) is non-crystalline resin, it is preferable toset the temperature in the range of [the Vicat softening point Tb minus20° C.] to [the Vicat softening point Tb plus 20° C.] of thethermoplastic resin (B). It is further preferable that for such a casewhere the thermoplastic resin (B) is crystalline resin, the temperatureis set in the range of [the Vicat softening point Tb minus 10° C.] ofthe thermoplastic resin (B) to [melting point minus 10° C.], and forsuch a case where the thermoplastic resin (B) is non-crystalline resin,the temperature is set in the range of [the Vicat softening point Tbminus 10° C.] to [the Vicat softening point Tb plus 10° C.] of thethermoplastic resin (B).

After the resin composition is shaped in the die 12, the melted resincomposition is cooled by controlling the temperature of die 12 by thetemperature control mechanism.

It is preferable that for such a case where the thermoplastic resin (B)is crystalline resin, a temperature of the die 12 (temperature atholding) is held for the preset time in the range of [crystallizationtemperature Tc minus 15° C.] to [crystallization temperature Tc plus 10°C.] of the thermoplastic resin (B), and it is further preferable to holdthe temperature for the preset time in the range of [crystallizationtemperature Tc minus 10° C.] to [crystallization temperature Tc] of thethermoplastic resin (B).

The preset time should be held in the range of 10 to 300 sec.,preferably in the range of 30 to 200 sec. Although the longer thisholing time, the better products are obtained, more than 300 sec is notdesirable since molding cycle becomes longer and the productivity isdeteriorated. This temperature range and holding time are determinedbased on the tolerance of lifting of the fibrous filler of resin moldingconsidering size of and thickness of resin molding, type of resin,presence of additives comprehensively.

After the resin composition is held for the preset time, the temperatureis controlled by the temperature control mechanism and lowered to such alevel as the resin molding can be taken out (temperature at cooling),for example, down to glass transition temperature Tg of thethermoplastic resin (B). This cooling rate is in the range which isnormally used for injection molding method.

When the thermoplastic resin (B) is non-crystalline resin, thetemperature is cooled down to a level which allows taking-out of theresin molding without holding it for the preset time.

After the resin molding is cooled down to the temperature which allowstaking-out, the clamping device 13 is operated, and moves the movabledie 12B so as to be separated from the fixed die 12A, releases clampingof the die 12, and mold opening of the die 12 is performed therebymanufacturing a resin molding.

As for the fibrous filler (A), glass fiber, carbon fiber, magnesiumsulfate fiber, potassium titanate fiber, titanium oxide fiber, magnesiumoxy-sulfate fiber or organic filler, organic synthetic or natural fibersand the like can be used. As for type of the fibers, continuous fiber,chopped strand and the like can be used. In this case, fiber diameter ofthe fibrous filler (A) should preferably be less than 25 μm.

As for the thermoplastic resin (B), for example, polypropylene,polyethylene, polystyrene, polycarbonate, ABS (acrylonitrile butadienestyrene copolymer), AES (acrylonitrile ethylene propylene rubber styrenecopolymer), AS (acrylonitrile styrene copolymer), modified PPE(polyphenylene ether), PPS (polyphenylene sulfide), nylon, SPS(syndiotactic polystyrene) and the like, and composite material thereofcan be used.

It is preferable that the resin composition contains not less than 7 wt% to less than 30 wt % of a fibrous fiber (A) and more than 70 wt % tonot exceeding 93 wt % of the thermoplastic resin (B). It is furtherpreferable that the fibrous filler (A) is contained not less than 10 wt% to not exceeding to 25 wt %.

According to the first embodiment as mentioned above, the followingresults are obtained:

When a resin composition in molten state is filled into the die andshaping is performed, temperature of the die 12 (temperature at shaping)is controlled by the temperature control mechanism and is set in therange of [the Vicat softening point Tb minus 20° C.] of thethermoplastic resin (B) to less than the melting point thereof, for sucha case where the thermoplastic resin (B) is crystalline resin, and isset in the range of [the Vicat softening point Tb minus 20° C.] to [theVicat softening point Tb plus 20° C.] for such a case where thethermoplastic resin (B) is non-crystalline resin. This operation allowsimproved fluidity of the resin composition at a contact of the die 12and the resin composition, suppresses lifting of the fibrous filler andat the same time, a molded surface of the die 12 is well transcribedonto the resin composition.

When the temperature is set in the range of [the Vicat softening pointTb minus 10° C.] of the thermoplastic resin (B) to [melting point minus10° C.] for such a case where the thermoplastic resin (B) is crystallineresin, and is set in the range of [the Vicat softening point Tb minus10° C.] to [the Vicat softening point Tb plus 10° C.] for such a casewhere the thermoplastic resin (B) is non-crystalline resin, moldingcycle is shortened and a molded surface of the die 12 is welltranscribed onto the resin composition.

Besides, after a resin composition is shaped in the die 12 and when ashaped resin composition is cooled, temperature of the die 12(temperature at holding) is set by the temperature control mechanism inthe range of [crystallization temperature Tc minus 10° C.] to[crystallization temperature Tc plus 10° C.] of the thermoplastic resin(B), and is held for the preset time for such a case where thethermoplastic resin (B) is crystalline resin. This operation allowscomprehensive control of the crystallization of the whole resin moldingas well as crystallization on the surface of the resin molding,suppression of lifting of the fibrous filler, elimination of warpagedeformation of the resin thereby contributing to improvement ofappearance of the whole resin molding and of dimensional accuracy.

When the temperature is held in the range of [crystallizationtemperature Tc minus 10° C.] to [crystallization temperature Tc] of thethermoplastic resin (B) for the preset time, molding cycle is shortened,and appearance of the whole resin molding and dimensional accuracy areimproved.

When the shaped resin composition is cooled after being shaped in thedie 12, it is cooled down to a level which allows taking-out of theresin molding without holding it for the preset time, for such a casewhere the thermoplastic resin (B) is non-crystalline. This considerationallows that if crystalline resin and non-crystalline resin arecontrolled under different cooling conditions, an appropriate moldingcycle is selected depending on the type of resin thereby improving theproductivity.

Further, by keeping a resin composition in the range of not less than 7wt % to less than 30 wt % of a fibrous fiber (A) and more than 70 wt %to not exceeding 93 wt % of the thermoplastic resin (B), appearance ofthe whole resin molding can be improved while maintaining the prescribedstrength.

In this case, if the resin composition contains more than 10 wt % toless than 25 wt % of the fibrous filler (A), physical properties of theresin molding can be improved adequately and at the same time, liftingof the fibrous filler (A) can be suppressed surely.

According to the abovementioned method, it is possible to manufacture aresin molding with the desired strength and suppressing lifting of thefibrous filler (A). When an embossing is provided on the molded surfaceof the die 12, by suppressing lifting of the fibrous filler (A), it ispossible to obtain a resin molding to which an emboss with nearly sameemboss depth provided on the molded surface is formed. When the moldedsurface of the die 12 is mirror finished, it is possible to obtain aresin molding with finer surface roughness and good surface gloss.

By providing a method for controlling die temperature such astemperature control mechanism to ordinary injection molding machine, itis possible to obtain a resin molding as mentioned above, andapplication fields of the present invention will be greatly expanded.

SECOND EMBODIMENT

In the following description, the same number as used in the above firstembodiment will be used for same constructions and parts, and theirdetailed explanations are omitted or simplified.

In the first embodiment, manufacturing of a resin molding is made byinjection molding method.

While the second embodiment differs in that hollow molding method isused for manufacturing of a resin molding.

FIG. 2 is a sectional view of a hollow molding machine used in themolding method relating to the second embodiment of the presentinvention.

Hollow molding machine 2 is a machine which produces resin moldinghaving the prescribed shape from resin composition in which fibrousfiller (A) and thermoplastic resin (B) are mixed, and has hollow moldingmachine body 21 and die 22.

Hollow molding machine body 21 performs melting and kneading of resincomposition and extrudes it in the form of parison P in between die 22,and has extrusion dice 211 which converts parison P being extruded intocylindrical form, parison sealing 212 which seals lower end part ofparison P, and gas injection pipe 213 which blows a gas into parison P.

The die 22 works so as to be freely opened or closed, and is used forgrasping parison P being extruded by the hollow molding machine body 21,and has a die temperature control pipe 221 for regulating temperature ofthe die 22, a cooling jacket 222 for cooling of the die 22 and a gasblowing pipe 223 for blowing of air from the die 22 to parison P inside.

The die temperature control pipe 221 regulates temperature of the die 22by circulating, for example, steam, heating oil and the like.

The cooling jacket 222 has a cooling medium inlet 222A being connectedto the outside and a cooling medium outlet 222B, a cooling medium isintroduced from the outside from the cooling medium inlet 222A andcooling medium outlet 222B for cooling of the die 22.

The gas blowing pipe 223 works so as to move forward or backwardsmoothly or from the inside to the outside of the die 22, protruded intothe die 22 and stabbed into parison P for blowing a gas into parison P.

Hereafter a method for molding a resin composition using above-mentionedhollow molding machine 2 will be described.

First, the hollow molding machine 2 is operated, and an extruder (notillustrated) performs melting and kneading of the resin composition andextrudes it. Normally using an accumulator, parison P in cylindricalfrom is extruded from the extrusion dice 211 between one set of moldopened die 22. Then the parison sealing 212 seals lower end part ofparison P thus extruded.

Second, air is blown from the gas injection pipe 213 to parison P insidefor pre-blowing purpose and the parison P is then inflated to someextent. Clamping of the die 22 then starts and the parison P is grasped.

At the time close to completion of clamping of the die 22, the gasinjection pipe 213 is protruded from die surface and is stabbed intoparison wall thereby introducing air into parison inside. Parison P theninflates, presses itself against the mold surface and brings itself intointimate contact with mold surface of the die 22 to perform shaping.

It is preferable that in a similar fashion as observed in the firstembodiment, temperature of the die 22 (temperature at shaping) is set bythe die temperature control pipe 221 in the range of [the Vicatsoftening point Tb minus 20° C.] of the thermoplastic resin (B) to lessthan the melting point thereof, for such a case where the thermoplasticresin (B) is crystalline resin, and in the range of [the Vicat softeningpoint Tb minus 20° C.] to [the Vicat softening point Tb plus 20° C.] ofthe thermoplastic resin (B), when the thermoplastic resin (B) isnon-crystalline resin. It is further preferable that the temperature isset in the range of [the Vicat softening point Tb minus 10° C.] to[melting point minus 10° C.] of the thermoplastic resin (B) when thethermoplastic resin (B) is crystalline resin, and in the range of [theVicat softening point Tb minus 10° C.] to [the Vicat softening pointplus 10° C.] of the thermoplastic resin (B) for such a case where thethermoplastic resin (B) is non-crystalline resin.

After a resin composition is shaped in the die 22, melted resincomposition in the die 22 is cooled by the cooling jacket 222.

It is preferable that in a similar way as observed in the firstembodiment, temperature of the die 22 (temperature at holding) is heldfor the preset time in the range of [crystallization temperature Tcminus 15° C.] to [crystallization temperature Tc plus 10° C.] of thethermoplastic resin (B) when the thermoplastic resin (B) is crystallineresin, and it is further preferable that the temperature is held for thepreset time in the range of [crystallization temperature Tc minus 10°C.] to [crystallization temperature Tc].

The preset time should be held in the range of 10 to 300 sec.,preferably in the range of 30 to 200 sec. Although the longer thisholing time, the better products are obtained, longer than 300 sec isnot desirable since molding cycle becomes longer and the productivity isdeteriorated. This temperature range and the holding time are determinedbased on the tolerance of lifting of the fibrous filler of resin moldingconsidering size of and thickness of resin molding, and type of resin,presence of additives and the like comprehensively.

When the die 22 is held at the prescribed temperature, a cooling mediumis circulated through the cooling jacket 222 while the heated medium isbeing maintained in the die temperature control pipe 221.

After keeping the prescribed temperature for the preset time, the mediumheated to the prescribed temperature in the die temperature control pipe221 and cooling jacket 222 is extracted, cooling medium at approximatelyroom temperature is introduced in the cooling jacket 222 in order tocool the temperature to such a level where the resin molding can betaken out (temperature at cooling), for example, down to glasstransition temperature Tg of the thermoplastic resin (B). This coolingrate is in the range which is normally used for hollow molding method.

The temperature is cooled down to a level which allows taking-out of theresin molding without holding it for the preset time, for such a casewhere the thermoplastic resin (B) is non-crystalline.

Resin molding is thus manufactured by the hollow molding methodaccording to processes mentioned above.

As for the resin composition (fibrous filler (A) and thermoplastic resin(B)), materials similar to those used in the first embodiment can beadopted.

According to the second embodiment as mentioned above, the followingresults are obtained:

Even with the hollow molding method using lower pressing pressure to themolded surface of the die 22 compared to the molding method mentioned inthe first embodiment, it is possible, by controlling the temperature ofdie 22, to improve die transcription rate through improvement offluidity of the resin composition, to suppress lifting of the fibrousfiller (A) and to improve appearance of the whole resin molding. Forsuch a case where the thermoplastic resin (B) is crystalline resin,crystallization of whole resin molding as well as crystallization on thesurface of the resin molding can be controlled which eliminates warpagedeformation and improves dimensional accuracy.

By providing a method for controlling die temperature such as dietemperature control pipe and cooling jacket and the like, it is possibleto obtain a resin molding as mentioned above, and application fields ofthe present invention will be greatly expanded.

EMBODIMENTS

Features and advantages of the present invention will be describedhereafter with reference to detailed examples.

Embodiment 1

In the embodiment 1, molding is made by hollow molding method accordingto the second embodiment under molding conditions shown hereafter, and aresin molding with 3 mm thickness at general part was manufactured.

(Molding Conditions)

Hollow molding machine: Model IPB-EPML-90S manufactured byIshikawajima-Harima Heavy Industries, Co., Ltd. [Die: 200 mmφ],Accumulator capacity: 13.5 liter, Die clamping pressure: 60 ton, Screwdiameter: 90 mm]

Die: Flat plate [Length: 600 mm, Width: 400 mm, Thickness: 25 mm, Moldedsurface: Mirror finish less than 0.5 S]

Die temperature; Temperature at shaping: 135° C.

-   -   Temperature at holding: 125° C.    -   Temperature at cooling: 60° C.

At shaping, heating is performed by circulating steam in the dietemperature control pipe 221. At temperature holding, water isintroduced into the cooling jacket 222 while steam is being circulatedin the die temperature control pipe 221. At cooling, steam in the dietemperature control pipe 221 is drained and water is passed through thecooling jacket 222.

Time for blowing: 150 sec.

Resin composition; Fibrous filler (A): GF chopped strand [Fiberdiameter: 10 μm, Fiber length: 0.5 mm]

-   -   Thermoplastic resin (B): B-PP: Propylene block copolymer        [Manufactured by Idemitsu Kosan Co., Ltd., IDEMITSU PP, E-185G,        MI: 0.3 g/10 min. (230° C., 2.16 kg load), Vicat softening        point: 145° C., Crystallization temperature: 125° C., Melting        point: 160° C.]    -   Amount of fibrous filler (A) added: 30 wt % (with regard to        resin composition 100 wt %)

A resin composition in which the fibrous filler (A) and thermoplasticresin (B) were dry blended was molded by the hollow molding methodaccording to the second embodiment.

Embodiment 2

In the embodiment 2, a resin molding was manufactured by the same methodas used in the embodiment 1 except that the molding conditions (resincomposition) in the embodiment 1 were altered as follows:

Resin composition; Fibrous filler (A): Glass fiber [Fiber diameter: 16μm, Fiber length: 4 mm]

-   -   Thermoplastic resin (B): Homopolypropylene [Vicat softening        point: 145° C., Crystallization temperature: 125° C., Melting        point: 160° C.]    -   Amount of fibrous filler (A) added: 20 wt % (with regard to        resin composition 100 wt %)

A resin composition in pellet form, in which glass fibers of the fibrousfiller (A) are arranged nearly in parallel in longitudinal direction andthe thermoplastic resin (B) is impregnated in the glass fibers, wasmolded by the hollow molding method according to the second embodiment.

Embodiment 3

In the embodiment 3, a resin molding was manufactured by the same methodas used in the embodiment 2 except that the molding conditions in theembodiment 2 were altered as follows:

Die; Molded surface: Embossing used for automobile interior decoration

Embodiment 4

In the embodiment 4, molding of a resin molding was performed by theinjection molding method according to the first embodiment under moldingconditions shown hereafter. Resin composition and die temperature sameas those used in the embodiment 2 were applied.

(Molding Conditions)

Injection molding machine: clamping pressure of 850 ton

Die; Flat plate [Length: 600 mm, Width: 400 mm, Thickness: 25 mm, Moldedsurface: Mirror finish less than 0.5S]

Embodiment 5

In the embodiment 5, a resin molding was manufactured by the same methodas used in the embodiment 2 except that the molding conditions in theembodiment 2 were altered as follows:

Die temperature: Temperature at holding: 115° C.

Embodiment 6

In the embodiment 6, a resin molding was manufactured by the same methodas used in the embodiment 2 except that the molding conditions in theembodiment 2 were altered as follows:

Die temperature: Temperature at holding: 135° C.

Embodiment 7

In the embodiment 7, a resin molding was manufactured by the same methodas used in the embodiment 1 except that the molding conditions in theembodiment 1 were altered as follows:

Resin composition; Thermoplastic resin (B): Shock resistance polystyrene(HIPS, manufactured by Idemitsu Kosan Co., Ltd., HT52). Namely,amorphous thermoplastic resin that is different from those used in theembodiments 1 through 6 was used.

Die temperature; Temperature at shaping: 130° C.

-   -   Temperature at cooling: 60° C.

In the embodiment 7, shaping of a resin composition was performed in thedie heated to 130° C. and after the preset time, cooling was performedat 60° C. Namely, different from embodiments 1 through 6, a process ofholding at the prescribed temperature after shaping of resin compositionwas not performed.

Embodiment 8

In the embodiment 8, molding of a resin molding was performed by thesame method as used in the embodiment 2 except that the moldingconditions in the embodiment 2 were altered as follows:

Die temperature; Temperature at holding: 100° C.

In the embodiment 8, shaping of a resin composition was performed in thedie heated to 130° C. and after shaping, it was held in the die heatedto 100° C. Cooling was started after holding for the preset time. Inother words, the embodiment 8 was adapted to the temperature range of([the Vicat softening point minus 20° C.] to less than melting point) atshaping according to Claim 1 of the present invention. The embodiment 8is the one in which holding temperature was varied from those in theembodiments 2, 5, and 6, to compare with these embodiments. Thetemperature at holding in the embodiment 8 does not fall into thetemperature range ([crystallization temperature minus 15° C.] to[crystallization temperature plus 10° C.]) according to claim 3 of thepresent invention.

COMPARISON EXAMPLE 1

In the comparison example 1, a resin molding was manufactured by thesame method as used in the embodiment 2 except that the moldingconditions in the embodiment 2 were altered as follows:

Die temperature; 80° C. (constant)

In the comparison example 1, shaping of a resin composition wasperformed in the die heated to 80° C. and cooling was started after thepreset time. Namely, different from embodiments 1 through 6, a processof holding at the prescribed temperature after shaping of crystallineresin composition was not performed.

COMPARISON EXAMPLE 2

In the comparison example 2, a resin molding was manufactured by thesame method as used in the comparison example 1 except that the moldingconditions in the comparison example 1 were altered as follows:

Die; molded surface: Embossing used for automobile interior decoration

COMPARISON EXAMPLE 3

In the comparison example 3, a resin molding was manufactured by thesame method as used in the comparison example 1 except that the moldingconditions in the comparison example 1 were altered as follows:

Die temperature; 160° C. (constant)

In the comparison example 3, shaping of a resin composition wasperformed in the die heated to 160° C. and cooling was started after thepreset time. Namely, different from embodiments 1 through 6, thetemperature at shaping did not fall into the prescription (outside [theVicat softening point minus 25° C.] to less than melting point or [theVicat softening point plus 25° C.]), and a process of holding at theprescribed temperature after shaping of crystalline resin compositionwas not performed.

COMPARISON EXAMPLE 4

In the comparison example 4, a resin molding was manufactured by thesame method as used in the embodiment 4 except that the moldingconditions in the embodiment 4 were altered as follows:

Die temperature; 40° C. (constant)

In the comparison example 4, shaping of a resin composition wasperformed in the die heated to 40° C. and cooling was started after thepreset time. Namely, different from embodiments 1 through 6, thetemperature at shaping did not fall into the prescription (outside [theVicat softening point minus 25° C.] to less than melting point or [theVicat softening point plus 25° C.]), and a process of holding at theprescribed temperature after shaping of crystalline resin compositionwas not performed.

COMPARISON EXAMPLE 5

In the comparison example 5, molding of a resin molding was performed bythe same method as used in the embodiment 7 except that the moldingconditions in the embodiment 7 were altered as follows:

Die temperature; Temperature at shaping: 80° C.

For resin moldings molded in the embodiments 1 through 8 and comparisonexamples 1 through 5, assessment was made according to the followingevaluation method:

(Evaluation Method)

1. Average Surface Roughness

Fine unevenness on the resin molding surface generated by mirrorfinished die is measured using a scanning type laser microscope (OlympusOptical Co., Ltd. make LSM-GM).

In other words, this sort of measurement is performed for resin moldingsmolded by embodiments 1, 2, and 4 through 8, and by comparison examples1, and 3 through 5.

2. Image Clarity

A sheet of section paper with 1 mm square is held over the resin moldingsurface obtained by mirror finished die, and judgment is made whether ornot square cells can be clearly visually discriminated from the imagereflected on the resin molding.

Namely, in similar manner of evaluation of the average surfaceroughness, this sort of measurement is performed for resin moldingsmolded by embodiments 1, 2, and 4 through 8, and by comparison examples1, and 3 through 5.

3. Die Transcription Rate for Molded Products

Emboss height on the resin molding surface obtained by a die subjectedto embossing is measured using a scanning type laser microscope (OlympusOptical Co., Ltd. make LSM-GM). At the same time, emboss depth on thedie surface subjected to embossing is measured. Then a ratio expressedby emboss height on the resin molding surface divided by emboss depth onthe die surface is calculated.

Namely, this sort of measurement is performed for resin moldings moldedby embodiment 3 and comparison example 2.

4. Shrinkage and Warpage

Presence of shrinkage on the resin molding surface is evaluatedvisually. Besides, a resin molding is placed on the flat plane andstatus of warpage deformation is evaluated visually.

Results of evaluation should be made as follows;

-   -   ∘: Good    -   Δ: Shrinkage or warpage is observed slightly.    -   x: Shrinkage or warpage is observed apparently.

Tables 1 and 2 show molding conditions and results of evaluation ofembodiments 1 through 8, comparison examples 1 through 5. TABLE 1Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5Embodiment 6 Embodiment 7 Materials used Short fiber Continuous

Short fiber G F fiber G F G F Crystalline Crystalline

Non-crystalline resin resin resin Fiber length(mm) 0.5 4

0.5 Amount of fiber added 30 20

30 (wt %) Molding method Hollow

Injection Hollow

molding molding molding Die At shaping 130

temperature At holding 125

115 135 — At cooling 60

Die surface Mirror

Embossing Mirror

finishing finishing Average surface 2 3 — 2 4 2 2 roughness (μm) Imageclarity Good Good — Good Good Good Good Die transcription rate — — 95 —— — — Shrinkage and warpage ∘ ∘ ∘ ∘ ∘ ∘ ∘

TABLE 2 Comparison Comparison Comparison Comparison Comparison example 1example 2 example 3 example 4 example 5 Materials used Short fiber

Short fiber G F G F Crystalline

Non-crystalline resin resin Fiber length(mm) 4

0.5 Amount of fiber added 20

30 (wt %) Molding method Hollow

Injection Hollow molding molding molding Die At shaping 80

160 40 80 temperature At holding — — — — — At cooling — — — — 60 Diesurface Mirror Embossing Mirror

finishing finishing Average surface 40 — Evaluation 2 2 roughness (μm)impossible due Image clarity Poor — to excessive Good Good Dietranscription rate — 50 deformation of — — resin molding Shrinkage andwarpage Δ Δ x ∘ ∘

Evaluation of embodiment 1 shows that average surface roughness is 2 μm,image clarity is good, and evaluation of shrinkage and warpage is good(o).

In the case average surface roughness of the fiber-reinforced resinmolding is more than 5 μm, fibrous filler (A) is easily exposed on thesurface of resin molding. Even if exposure on the surface of resinmolding is not recognized, unevenness is easily formed on the surface bythe resin filler (A). It is considered that in the case of theembodiment 1, lifting of the fibrous filler (A) is suppressed due tothat average surface roughness is 2 μm.

In the case image clarity is poor, the following factors may beresponsible in many cases:

For example, surface of the resin molding is rough, anti-scratchingfeature and high-gloss feature of the resin molding are notsatisfactory, or surface of the resin molding is distorted.

In the case of the embodiment 1, from the fact image clarity of thisresin molding is good, it is considered that surface gloss is good,surface of the resin molding is free from distortion, andanti-scratching feature is satisfactory.

Besides, due to that evaluation of shrinkage and warpage of this resinmolding is good, it can be confirmed that the resin molding has goodappearance and high dimensional accuracy.

Therefore, in the embodiment 1, even when 30 wt % fibrous filler (A) isadded, a resin molding with good appearance, less warpage deformation,and excellent dimensional stability could be molded with suppressinglifting of the fibrous filler (A).

In the case of the embodiment 2, results obtained are average surfaceroughness of 3 μm, good image clarity, and good evaluation (o) forshrinkage and warpage.

Therefore, as is the case of the embodiments 1, a resin molding withgood appearance, less warpage deformation, and excellent dimensionalstability could be molded with suppressing lifting of the fibrous filler(A).

In the case of the embodiment 3, results obtained are die transcriptionrate of 95% and good evaluation (o) for shrinkage and warpage.

In the case die transcription rate is less than 90%, average surfaceroughness of the resin molding exceeds 5 μm in many cases. Namely, thefibrous filler (A) is exposed at surface of the resin molding in manycases. In the case of the embodiment 3, from the fact die transcriptionrate is 95%, lifting of the fibrous filler (A) is suppressed and theemboss is transcribed surely resulting in good appearance.

Besides, due to that evaluation of shrinkage and warpage is good, it canbe confirmed that the resin molding has good appearance and highdimensional accuracy.

Therefore, in the case of the embodiment 3, as is the cases of theembodiments 1 and 2,

a resin molding with good appearance, less warpage deformation, andexcellent dimensional stability could be molded while suppressinglifting of the fibrous filler (A).

In the case of the embodiment 4, as is the case of the embodiment 1,results obtained are average surface roughness of 2 μm, good imageclarity, and good evaluation (∘) for shrinkage and warpage.

Therefore, in the embodiment 4, as is the cases of the embodiments 1 and3, a resin molding with good appearance, less warpage deformation, andexcellent dimensional stability could be molded with suppressing liftingof the fibrous filler (A).

In the case of the embodiment 5, results obtained are average surfaceroughness of 4 μm, good image clarity and good evaluation (∘) forshrinkage and warpage.

Therefore, in the embodiment 5, as is the cases of the embodiments 1 and4, a resin molding with good appearance, less warpage deformation, andexcellent dimensional stability could be molded while suppressinglifting of the fibrous filler (A).

In the case of the embodiment 6, as is the cases of the embodiments 1and 4, results obtained are average surface roughness of 2 μm, goodimage clarity and good evaluation (∘) for shrinkage and warpage.

Therefore, in the embodiment 6, as is the cases of the embodiments 1 and5, a resin molding with good appearance, less warpage deformation, andexcellent dimensional stability could be molded with suppressing liftingof the fibrous filler (A).

In the case of the embodiment 7, as is the cases of the embodiments 1, 4or 6, results obtained are average surface roughness of 2 μm, good imageclarity and good evaluation (∘) for shrinkage and warpage.

Therefore, in the embodiment 6, as is the cases of the embodiments 1 and5, a resin molding with good appearance, less warpage deformation, andexcellent dimensional stability could be molded while suppressinglifting of the fibrous filler (A).

In the case of the embodiment 8, results obtained are average surfaceroughness of 10 μm, poor image clarity and good evaluation (∘) forshrinkage and warpage.

In the case of the embodiment 8, since the temperature at holding isoutside the prescription, average surface roughness is more than 5 μm.However, the temperature at shaping is within the prescription andtherefore, comparatively lower average surface roughness (10 μm)compared to the comparison example 4 is attained. If compared to theembodiment 1 or 6, it is understood that the temperature at holdingshould preferably be in the range of [crystallization temperature minus15° C.] to [crystallization temperature plus 10° C.].

In the case of the comparison example 1, results are average surfaceroughness of 40 μm, poor image clarity and evaluation of shrinkage andwarpage is A.

Therefore, from average surface roughness and result of image clarity,it is considered that suppression of lifting of the fibrous filler (A)was not possible and a resin molding with good appearance could not beobtained.

In the case of the comparison example 2, results obtained are dietranscription rate of 50% and evaluation of shrinkage and warpage is A.

Therefore, from the result of die transcription rate, it is consideredthat suppression of lifting of the fibrous filler (A) was not possibleand a resin molding with good appearance could not be obtained.

In the case of the comparison example 3, evaluation was not possible dueto excessive deformations of the resin molding.

Therefore, if the die temperature during molding was not appropriate,warpage deformation occurred, and it was not possible to obtain a resinmolding with high dimensional accuracy.

In the case of the comparison example 4, results are average surfaceroughness of 50 μm, poor image clarity and good evaluation (∘) forshrinkage and warpage.

Therefore, it is considered that although warpage deformation of theresin molding was avoided, from the results of average surface roughnessand image clarity, suppression of lifting of the fibrous filler (A) wasnot possible, and it was not possible to obtain a resin molding withgood appearance.

In the case of the comparison example 5, results obtained are averagesurface roughness of 30 μm, poor image clarity and good evaluation (∘)for shrinkage and warpage.

Therefore, as is the case of the comparison example 4, it is consideredthat although warpage deformation of the resin molding was avoided, fromthe results of average surface roughness and image clarity, suppressionof lifting of the fibrous filler (A) was not possible, and it was notpossible to obtain a resin molding with good appearance.

[Modifications]

Specific embodiments of the present invention have been describedherein, however the present invention is not restricted within theaforementioned methods, but various modifications or improvements may beincluded in scope of the invention.

The temperature control mechanism, die temperature control pipe, andcooling jacket described in the embodiments mentioned above to exemplifymethods for controlling die temperature do not constitute a limit of thepresent invention. For example, as methods for controlling dietemperature, a method for circulating heating medium in the die, amethod for heating electrically such as resistance heating, dielectricheating and the like, a die that incorporates heating method in its bodymay be adopted. Alternatively, such a method that heats die surfaceselectively for gas flame heating from die surface side may be adopted.Further, for cooling, such a method that circulates a cooling medium inthe die may be adopted.

Further, in each of the foregoing embodiments, antioxidant, antistaticagent, ultraviolet absorber, light stabilizer, flame retarder,flame-retardant additives, pigment, dispersant, nucleator and the likemay be added as necessary to the resin composition.

Further, the method for molding a resin molding to which fibrous filler(A) is added is not limited to each of the foregoing embodiments. Forexample, vacuum pressure molding and the like may be adopted. In otherwords, any molding method is acceptable so long as a die is used.

INDUSTRIAL APPLICABILITY

The present invention may be used for resin moldings to which fibrousfiller is added and molding method thereof, and utilized in automobileand housing facility industries and the like where rigidity andappearance are required. Particularly, the present invention may be usedin the automobile industry for instrumental panel parts, door parts,body panel, floor lid, side steps and the like. Further, the presentinvention may be used in the housing facility industry for prefabricatedbath parts, assembled furniture, doors, roads, railroad sound-proofwalls and the like.

1. A molding method for manufacturing a resin molding by charging aresin composition including fibrous filler (A) and resin (B) in moltenstate into a die by injection, wherein the resin composition containsnot less than 7 wt % to less than 30 wt % of the fibrous filler (A) andmore than 70 wt % to not exceeding 93 wt % of the resin (B), and thatcomprises the steps of; (a) charging the resin composition in moltenstate into the die for shaping purpose when a temperature of the die isin the range of [the Vicat softening point minus 20° C.] of the resin(B) to less than a melting point thereof, when the resin (B) iscrystalline resin, or charging the resin composition in molten stateinto the die for shaping purpose when a temperature of the die is in therange of [the Vicat softening point minus 20° C.] to [the Vicatsoftening point plus 20° C.] of the resin (B), when the resin (B) isnon-crystalline resin; and (b) cooling down the die to a temperaturewhich allows taking-out of a molded product, after the shaping isperformed.
 2. A molding method for manufacturing a resin molding byextruding a resin composition including fibrous filler (A) and resin (B)to be converted into a molten parison, holding the parison within a die,and by blowing gas into the parison inside, wherein the resincomposition contains more than 7 wt % to less than 30 wt % of thefibrous filler (A) and more than 70 wt % to less than 93 wt % of theresin (B), and that comprises the steps of; (a) blowing gas into theparison inside for shaping purpose when a temperature of the die is inthe range of [the Vicat softening point minus 20° C.] of the resin (B)to less than a melting point thereof, when the resin (B) is crystallineresin, or blowing a gas into the parison inside for shaping purpose whena temperature of the die is in the range of [the Vicat softening pointminus 20° C.] to [the Vicat softening point plus 20° C.] of the resin(B), when the resin (B) is non-crystalline resin; and (b) cooling downthe die to temperature which allows taking-out of a molded product afterthe shaping is performed
 3. The molding method according to claim 1,wherein if the resin (B) is crystalline resin, after shaping of theresin composition is performed, a temperature of the die is held forpreset period in the range of [crystallization temperature minus 15° C.]to [crystallization temperature plus 10° C.] of the resin (B). 4-10.(canceled)
 11. The molding method according to claim 2, wherein if theresin (B) is crystalline resin, after shaping of the resin compositionis performed, a temperature of the die is held for preset period in therange of [crystallization temperature minus 15° C.] to [crystallizationtemperature plus 10° C.] of the resin (B).
 12. The molding methodaccording to claim 1, wherein shaping of the resin composition isperformed when a temperature of the die is in the range of [the Vicatsoftening temperature minus 10° C.] of the resin (B) to [melting pointminus 10° C.], when the resin (B) is crystalline resin, or performedwhen a temperature of the die is in the range of [the Vicat softeningtemperature minus 10° C.] to [the Vicat softening temperature plus 10°C.] of the resin (B), when the resin (B) is non-crystalline resin. 13.The molding method according to claim 2, wherein shaping of the resincomposition is performed when a temperature of the die is in the rangeof [the Vicat softening temperature minus 10° C.] of the resin (B) to[melting point minus 10° C.], when the resin (B) is crystalline resin,or performed when a temperature of the die is in the range of [the Vicatsoftening temperature minus 10° C.] to [the Vicat softening temperatureplus 10° C.] of the resin (B), when the resin (B) is non-crystallineresin.
 14. The molding method according to claim 1, wherein aftershaping of the resin composition is performed, a temperature of the dieis held for preset period in the range of [crystallization temperatureminus 10° C.] to [crystallization temperature] of the resin (B), whenthe resin (B) is crystalline resin.
 15. The molding method according toclaim 2, wherein after shaping of the resin composition is performed, atemperature of the die is held for preset period in the range of[crystallization temperature minus 10° C.] to [crystallizationtemperature] of the resin (B), when the resin (B) is crystalline resin.16. The molding method according to claim 1, wherein the resincomposition contains not less than 10 wt % to not exceeding to 25 wt %of the fibrous filler (A).
 17. The molding method according to claim 2,wherein the resin composition contains not less than 10 wt % to notexceeding to 25 wt % of the fibrous filler (A).
 18. A resin moldingmanufactured by the molding method of claim
 1. 19. A resin moldingmanufactured by the molding method of claim
 2. 20. A resin moldingcontaining not less than 7 wt % to less than 30 wt % of a fibrous fiber(A) and more than 70 wt % to not exceeding 93 wt % of a resin (B),wherein surface roughness is less than 5 μm and an image representationof 1 mm square rectangular frame reflected on the surface can bediscriminated.
 21. A resin molding having an emboss on the surface andcontaining not less than 7 wt % to less than 30 wt % of a fibrous fiber(A) and more than 70 wt % to not exceeding 93 wt % of a resin (B), andis characterized by either one of the following 1 or
 2. (1) Dietranscription rate is more than 90% for such a case where emboss isprovided over whole surface of a resin molding; (2) Die transcriptionrate is more than 90% and surface roughness of such an area where thereis no emboss is less than 5 μm for such a case where emboss is providedin part of a resin molding.
 22. The resin molding according to claim 20,wherein the resin composition contains not less than 10 wt % to notexceeding to 25 wt % of the fibrous filler (A).
 23. The resin moldingaccording to claim 21, wherein the resin composition contains not lessthan 10 wt % to not exceeding to 25 wt % of the fibrous filler (A).